In the case of a conventional adhesive sheet, paths are formed in an adhesive surface of the adhesive sheet in order to remove air or moisture that may be generated at the time of attachment of the adhesive sheet. In order to form the paths, there has been used a method of adjusting the shape of the surface of a release paper or a release film before silicon treatment such that the shape is transferred to the surface of an adhesive layer, whereby air or moisture is easily removed using the paths formed as the result thereof.
However, the adhesive force of the conventional adhesive sheet is reduced over time, whereby the adhesive layer is separated or the shape of the adhesive layer is changed. As a result, the paths may not properly function to discharge air or moisture.
In addition, water must be used when the conventional adhesive sheet is attached to the surface of a target for attachment. In the winter season, in which the temperature is low, however, the water may easily freeze.
Furthermore, in the case in which an adhesive sheet having no paths, through which air is discharged from the adhesive layer, is used, a film is cut using a sharpened tool such as a cutter such that an air bubble layer is removed in order to remove air bubbles that are trapped sporadically at the time of attachment of the adhesive sheet. After the lapse of a predetermined amount of time, however, the cut portions in the film may open, whereby a product becomes defective.
In order to solve the above problem, there has been developed an adhesive sheet having air discharge paths that are defined in a patterned adhesive layer formed on an adhesive surface of the adhesive sheet in order to discharge air that may be generated at the time of attachment of the adhesive sheet to the outside while maintaining the adhesive force of the adhesive sheet.
However, the air discharge paths in the adhesive sheet are maintained even after the attachment of the adhesive sheet. As a result, air or moisture may be reintroduced into the adhesive sheet through the air discharge paths, whereby the period during which the adhesive sheet remains attached is shortened.